Wrist-pin.



- R. E, BENNER WRIST PIN.

APPLICATION FILED DEC. 7, 1914.

IL 9 1 9?,33 3 a Patented Sept. 5, 1916.

WNEssEs IHVEflTOYF wm awm W f Mafi JITTORHEY sov stares. Pa

'RUSSELL E. BENNER, or DETROIT, MICHIGAN.

WRIST-PIN.

Specification of Letters Patent.

Patented Sept. 5, 1916.

Application fil ed December 7, 1914. Se'rial 1\To. 875,753.

to make and use the samefrfernce being had to the accom )an in drawin s which form a part of this specification.

vThis invention relates to tubular. wrist pins having a transverse groove-for the reception of the fastening bolt, and the method ofconstructing the same. When this groove is made bycutting away the metal of the pin, the wall between the groove and the inner periphery of thepin is rendered thin, and when the pin is hardened-so that the material is not homogeneous this thin portion is differently effected to break.

produce at the same time a corresponding than the rest 'of the pin and the pin is liable As hitherto constructed. the wall of the pin has been of uniform thickness. and the groove 1*) hasbeen produced by milling or otherwise cutting away the metal of said wall. Thethickness o1 the wall between the b ttom of the groove and the inner surface of thezpin is thus greatly reduced. IVhen the pin is surface hardened, the hardening extends inwardly for a certain distance,

and follows the contour of the surface, so that it affects practically all that portion of thewall which is of reduced thickness, 'as above noted,rendering the same brittle, and because of its thinness liable to rupture.

In order to avoid this dii'lieulty, I produce the groove E by pressing'the wall inwardly so as not merely to form the groove IQ on the outer surface of the pin, but also a corresponding projection F on the inner surface. In this way I keep the thickness of the wall substantially uniform everywhere. Hence the hardened outer portion, th depth of which is indicated by the dotted line in Fig. 2. is'backed by the tough un- Q hardened metal between the groove and 1nner periphery of the pin-and the wall is as strong at this point as at other points.

projection on the inside of the pin. This" makes the wall everywhere of substantially I uniform thickness, and insures the homogeneity of the finished pin. This construction also produces a pin that may be easily 'manipulated for grinding.

In the accomianvin drawin s: Fi ure l t 2 h D it, shows an engine piston with its connecting rod pivoted in place by means of my lmproved wrist pm. said pin, the end ot the connecting rod ad acent thereto, and a portion of said )iStOIl bein shown in section. i

Fig. 2, shows the wrist pin. separately, a part being broken away to exhibit the transverse gi'oove in longitudinal section. Fig. 3, is a top view of the wrist pin, showing the transverse groove. Figs. 4 and 5, respectively, are side and end views of a tool for holding and adjusting the pin for grinding. I

The wrist pin A is of steel and in the usual tubular form. It connects the piston B and the connecting rod C in the usual way, being seated at its ends in bearings in the piston and passing through the opening in the connecting rod, in which it is clamped by means of the. bolt D, said bolt being received in the groove E formed transversely in said pin. 1

To turn the pin a tool shown in Figs. 4; and 5 is employed. This tool resembles a.,

socket wrench and is provided with the handle a. and a cylindrical shank 7/, the latter being cut away at c. The shank in the tube of which the pin is inadefthe cut away portion (1 engaging the portioul of the wall that is bent inward. The centerbt the grinder may be formed like the slmuk I).

What I claim is:

1. A tubular steel wrist pin having an inresponding projection tron] its interior surface, the wall of said pin being of substantially uniform thickness, said pin libeing hardened for the purpose described.

dentation in its exterior surface and a. cor- 2. A tubular steel wrist pin having on its exterior atransverse groove and on its in terior a. pro ection correspondingthereto, the wall of said pin being oi substantially uniform th ckness. said pin being hardened 10 for the purpose described.

3. A tubular steel wrist pin having on its exterior a transverse groove and on its interior a projection corresponding thereto, the said groove and projection being simultaneously formed by inwardly pressing the wall of said pin, said pin being hardened fol-the purpose described.

t. The method of making a wrist pin consisting in taking a cylindrical tubular piece of steel and pressing the wall thereof inward to producea transverse groove in itsperiphery and then hardening the steel.

5.7lhe method of making a wrist pin, consisting in taking a cylindrical tubular piece of steel and pressing the wall thereof inward at one place so as to form a depres- 

